PEM fuel cells use electrocatalysts for the oxidation of hydrogen at the anode and reduction of oxygen (in air) at the cathode. Currently, platinum (Pt) and its alloys supported on high surface area carbons are the only feasible electrocatalyst for proton exchange membrane (PEM) fuel cell systems. However, a significant problem hindering large-scale implementation of PEM fuel cell technology is the loss of performance during automotive vehicle cycling and extended operation. Recent investigations of the deterioration of cell performance have revealed that a considerable part of the performance loss is due to the degradation of the electrocatalyst. Although carbon has been considered as a most suitable catalyst support owning to its low cost, good electron conductivity, high surface area, morphology allowing gas diffusion, and chemical stability; corrosion of carbon supports on the cathode side of PEM fuel cells is emerging as a challenging issue for long-term stability of PEM fuel cells.